Fire fighting foam generator



Nov. 27, 1962 R. w. BARNES FIRE FIGHTING FOAM GENERATOR 2 Sheets-Sheet 1 Filed Nov. 2, 1959 INVENTOR Robert W. Barnes ATTORNEY R. w. BARNES 3,065,797

Nov. 27, 1962 NG FOAM GENERATOR FIRE FIGHTI 2 Sheets-Sheet 2.

Filed Nov. 2,

\NVENTOR Roberi W. Barnes ATTORNEY United States Patent Ofiice 3,65,??? Patented Nov. 27., 1962 3,665,797 FIRE FIGHTING FOAM GENERATUR Robert W. Barnes, Penn Hills Township, Allegheny Qounty, Pa. (319 Walnut fin, Greenshnrg, Fa.) Filied Nov. 2, 1959, Ser. No. 85%,216 6 Claims. (Cl. 16915) This invention relates to fire fighting equipment, and more particularly to apparatus of the type described adapted to generate a mass of water-containing foam or bubbles capable of extinguishing a fire.

Recently, a method was developed for fighting fires wherein a foam plug (i.e., mass of bubbles) is generated by spraying a solution containing a wetting agent onto a woven fabric net having natural or induced air currents flowing therethrough. The net is loosely knit from cotton yarn or some other highly absorbent material, the arrangement being such that a plurality of apertures are formed in the material across which bubbles may form. When the solution containing a wetting agent is thus sprayed onto the net, it will be absorbed by the cotton yarn until such time as the yarn becomes saturated. At this point the solution bridges across the various apertures in the net; and the air currents flowing through the net cause the formation of bubbles at these apertures. The resulting foam plug then fills the entire area in front of the net and travels to the fire zone Where it forms steam which eventually smothers the fire.

As will be understood, the method described above is particularly adapted for use in fighting fires within enclosures such as, for example, those occurring-in coal mines and in buildings. In such enclosures heat, smoke and other obstacles make it extremely difiicult to get close enough to the fire zone where the water jet from a fire hose can be applied directly onto the fire. The problem is particularly acute in the case of mine fires where the lowness of the mine roof limits the range of the jet from a hose. By using a foam generator, however, the foam plug or mass of bubbles can effectively travel around corners and will fill the entire mine shaft or building so that the foam generating equipment can be located at a considerable distance from the fire zone, and the problem of directing a water jet onto the fire is eliminated. In the case of building fires, the foam also has the advantage of eliminating water damage since, although the foam will fill the entire area of the building surrounding the fire, its water content is relatively small and will not soak furniture and other fixtures within the building.

A foam generator usually takes the form of a wind tunnel having a fan at one end and a woven fabric net at the other end. Nozzles are provided between the fan and the net for spraying a solution containing a wetting agent onto the net. The generator may be transportable or it may be permanently installed within a building and arranged to be turned on automatically in response to a fire in much the same way as an automatic sprinkler system. In either case, a net woven from cotton yarn or other similar material tends to rot after a certain amount of time so that it is altogether desirable to provide a foam-forming instrumentality in a foam generator which will not deteriorate after prolonged periods. This is particularly desirable in the case of permanent installations where the generator may be inactive for years before it becomes necessary to use it.

The present invention has as its primary object the provision of a new and improved fire-fighting foam generator in which none of the parts will deteriorate after prolonged periods of time.

More specifically, an object of the invention resides in the provision of a new and improved foam-forming wall for a foam generator of the type described above.

Another object of the invention is to provide a firefighting foam generator in which the necessity for spraying nozzles is eliminated.

Still another object of the invention is to provide means, in combination with a fire fighting foam generator, for directing and guiding a foam plug to a fire zone without filling the entire area surrounding the generator and the fire with foam.

As will become apparent from the following detailed description, the invention comprises a wind tunnel having a fan at one end which forces air axially through the tunnel. Positioned at the opposite end of the tunnel is a foam-forming structure. In contrast to previous foam generators, however, the foam-forming structure of the present invention comprises a pair of corrugated and closely spaced parallel walls which, in most cases, are inclined with respect to vertical. The walls are fabricated from metal, plastic or some other similar material; and the perforations or apertures in the one wall are usually smaller and more closely spaced than those in the other. In one illustrative embodiment of the invention, the one wall may take the form of a mesh or screen while the other wall is a punched metal sheet. A solution containing a wetting'agent is injected into the top of the space between the walls whereby it will flow downwardly between the walls and, because of capillary action, will bridge across the various apertures. The air flowing through the tunnel will then form bubbles at these apertures. Either one of the walls may face the fan; however, larger foam bubbles will be formed when the plate with the smaller apertures faces the fan than when the opposite condition exists. Since the plates are formed from metal or some other non-deteriorating material, they may be used indefinitely without requiring replacement from time to time.

The above and other objects and features of the invention will become apparent from the following detailed description taken in connection with the accompanying drawings which form a part of this specification and in which:

FIGURE 1 is a cross sectional view, taken along a vertical plane, showing one embodiment of the invention;

FIG. 2 is a partially broken away view showing the structure of the foam-forming walls of the invention;

FIG. 3 is a cross sectional View, taken along line IIIIII of FIG. 2, showing the construction of the means for feeding a solution containing a wetting agent into the space between the parallel, perforated walls shown in FIGS. 1 and 2;

FIG. 4 is an enlarged cross-sectional view of the parallel foam-forming walls of the invention;

FIGS. SA-SE are enlarged views showing the stage-bystage formation of a foam bubble in the apparatus of FIG. 1;

FIG. 6 illustrates the appearance of the beginning of a foam plug generated by the apparatus of the invention;

FIG. 7 is an illustration of a device for directing and guiding a foam plug to a fire zone without filling the entire area surrounding the generator; and

FIG. 8 is an illustration of another embodiment of the invention wherein the parallel foam-forming walls are reversed with respect to those shown in FIG. 1.

Referring to FIGS. 1 and 2, the embodiment of the invention shown comprises a wind tunnel 10 which is fabricated from three sections l2, l4 and 16. Sections 12 and 16 may be rectangular or circular in cross section, depending upon requirements, and have their cross sectional areas fixed along their lengths. Sections 14, however, is tapered and connects section 12 of larger cross sectional area to section 16 of smaller cross sectional area. As shown, bolts or other similar fastening means may be used to secure the respective sections together.

Positioned within section 16 of small cross sectional area is a fan 18 having a rotor 26 with a plurality of fan blades 22 aflixed thereto. Fan 18 is also provided with a stationary housing 24 having a plurality of vanes 26 extending radially outwardly toward the Wall of section 16. As will be understood, the fan 18 creates an air current which travels through the wind tunnel from left to right as shown in FIG. 1.

Welded or otherwise securely fastened to the inner periphery of section 12 is an inclined foam-forming assembly, generally indicated at 28. The assembly 28 is best shown in FIG. 2 and comprises a first sheet or wall 30 having a plurality of openings 32 punched therein. The openings 32 are flared as shown in FIG. 1 due to the particular punching operation employed; however, such flared openings are not necessary for the successful operation of the device. Parallel to wall 3% and closely adjacent thereto is a second wall 34 which, in the embodiment of the invention shown herein, comprises a mash or screen having a plurality of openings therein. It should be understood, however, that the wall 34 may also be a punched plate as is the wall 30. In addition, under certain circumstances, it may not be necessary for the walls to be inclined at all. Ordinarily, the apertures or openings in one of the walls will be smaller and more closely spaced than those in the other wall; however, this again is a factor which can best be deter mined by experiment.

Extending across the top of walls 30 and 34 is a conduit 36. As is shown in FIG. 3, the conduit 36 has a slot 38 extending along its axial length. This slot is located on the circumference of conduit 36 whereby it will direct a solution containing a wetting agent into the space between the parallel walls 36 and 34. From conduit 36, the solution will flow downwardly through the inclined walls 30 and 34 until it reaches a collecting conduit 40 which is similar in construction to the conduit 36 already described.

The wetting agent solution is conveyed to conduit 36 from a valve 42 which serves to mix water from conduit 44 with a wetting agent from conduit 46. Any suitable wetting agent in conduit 46 may be used which will generate bubbles across the apertures of the foam-forming assembly 28. However, as an example, 30% active ammonium lauryl sulfate dissolved in water in a proportion of about 15% active material by weight to give a concentrate in conduit 46 which is then mixed with water in conduit 44 at the rate of about 3% by volume has been found to give sufficiently good results in generating the foam material.

In FIG. 4, it will be seen that as the wetting agent solution flows downwardly through the walls 30 and 34 it will form small pockets of liquid 48 at the edges of the apertures 32 in wall 30 After the liquid in these pockets builds up to a certain level, it will bridge across the apertures 32 and likewise, by capillary action, will bridge across the various apertures in the screen 34. The fire-fighting foam is produced by the air blowing bubbles from the films of liquid which are stretched over the holes or apertures 32 in wall 30. The stage-by-stage formation of the bubble is shown in FIGS. A-5E. The solution containing a wetting agent will be injected through conduit 36 at a constant rate into the top of the space between the walls 30 and 34. This solution will gradually build up in the space between the walls as shown in FIG. 5A until it comes into contact with the screen or wall 34 as shown in FIG. 53. At this point the solution will bridge across the various small apertures in the screen 34 by capillary action to produce a film of liquid across the aperture 32. Thereafter, the air currents flowing through the aperture 32 will gradually blow a bubble as shown in FIGS. 50 and 5D; and, after this bubble leaves the aperture, a second film is formed across the screen and a second bubble blown as shown in FIG. 5E. The resulting mass of bubbles formed by the generator is shown in FIG. 6. A foam plug, identified by the numeral 50, will gradually fill the various rooms of a building or a mine shaft, as the case may be, until it reaches the fire zone where the heat of the fire will vaporize the bubbles. The resulting steam then smothers the fire.

Referring to FIG. 7, there is shown a polyethylene or other similar bag 52 connected to the discharge end of the foam generator. The polyethylene bag 52 is coiled as shown such that when the foam generator is turned on, the resulting foam plug will gradually uncoil the polyethylene bag while at the same time forming an elongated tube filled with foam. This action will continue until the coiled end of the polyethylene bag reaches the fire zone. The heat of the fire will then melt the polyethylene, thereby opening the end of the foam-filled tube which then directs the foam plug directly onto the blaze. In this manner, the foam plug may be directed directly onto the fire zone Without filling the entire area surrounding it.

In FIG. 8 another embodiment of the invention is shown wherein the inclined walls 30 and 34 are reversed. That is, the wall or screen 34 with the smaller apertures now faces the outlet of the generator whereas the wall 3 with the larger apertures faces the fan 18. The operation of this generator is essentially the same as that shown in FIG. 1 except that the foam bubbles are now blown across the smaller apertures of the screen 34 while the apertures in wall 30 merely serve to direct air from fan 18 onto the screen.

' Although the invention has been shown in connection with certain specific embodiments, it will be readily apparent to those skilled in the art that various changes in form and arrangement of parts may be made to suit requirements without departing from the spirit and scope of the invention.

I claim as my invention:

1. In a fire fighting foam generator of the type which includes an elongated wind tunnel having means at its one end for forcing air axially through the tunnel and foam-forming means at the opposite end of the tunnel; the improvement in said foam-formin g means which comprises first and second closely spaced parallel walls extending across said opposite end of the tunnel at an oblique angle with respect to vertical, each of said walls having a plurality of closely spaced apertures therein with the apertures in the wall facing said one end of the tunnel being smaller and more closely spaced than those in the wall facing said opposite end, valve means for mixing water and a bubble-forming wetting agent, and conduit means connected to said valve means and having a discharge opening in the space between the walls at the tops thereof for injecting the mixture of water and wetting agent directly into the space between said walls whereby the solution will bridge across the aperture in the wall facing said opposite end of the tunnel while the air flowing through the tunnel forms bubbles at said apertures.

2. In a fire fighting foam generator of the type which includes an elongated wind tunnel having means at its one end for forcing air axially through the tunnel and foam-forming means at the opposite end of the tunnel; the improvement in said foam-formin g means which comprises first and second closely spaced parallel walls extending across said opposite end of the tunnel at an oblique angle with respect to vertical, each of said walls having a plurality of closely spaced apertures therein with the apertures in the wall facing said one end of the tunnel being larger and more widely spaced than those in the wall facing said opposite end, a liquid proportioning device for mixing water and a bubble-forming wetting agent, and condui' means connected to said proportioning device and having a discharge opening in the space between said walls at the tops thereof for injecting the mixture of water and wetting agent directly into the space between said walls.

3. In a fire fighting foam generator of the type which includes an elongated wind tunnel having means at its one end for forcing air axially through the tunnel and foamforming means at the opposite end of the tunnel; the improvement in said foam-forming means which comprises first and second closely spaced parallel walls extending across said opposite end of the tunnel, each of said walls having a plurality of closely spaced apertures therein with the apertures in one wall being smaller and more closely spaced than those in the other Wall, a liquid proportioning device for mixing water and a bubble-forming wetting agent, and conduit means connected to said proportioning device and having a discharge opening in the space between the walls at the tops thereof for injecting the mixture of water and wetting agent directly into the space between said walls whereby the mixture will flow down through the space between the walls and bridge across the apertures in one of the walls while air'traveling through the tunnel forms bubbles at said apertures.

4. A fire fighting foam generator comprising an elongated housing forming a wind tunnel, means at one end of said tunnel for forcing air axially therethrough, a pair of spaced parallel Walls extending across the other end of the tunnel, said walls being inclined whereby a liquid injected into the top of the space between the Walls will flow downwardly to the bottoms of the walls, each of said walls having a plurality of apertures therein with the apertures in one wall being smaller and more closely spaced than those in the other wall, a liquid proportioning device for mixing water and a bubble-forming wetting agent, and conduit means connected to said proportioning device and having a discharge opening in the space between the walls at the tops thereof for injecting the mixture of water and wetting agent directly into the space between the walls at the tops thereof.

5. A fire fighting foam generator comprising an elongated housing forming a wind tunnel, means at one end of said tunnel for forcing air axially therethrough, an inclined perforated wall extending across the other end of said tunnel, a screen member closely spaced from said perforated wall and extending parallel thereto, the openings in said screen member being smaller and more closely spaced than the perforations in said Wall, a liquid proportioning device for mixing water and a bubble-forming wetting agent, and a conduit connected to said proportioning device and having a discharge opening in the space between said screen and wall for injecting the mixture of water and bubble-forming wetting agent directly into the space between the screen and the wall at the tops thereof.

6. A fire fighting foam generator comprising an elongated housing forming a wind tunnel, means at one end of said tunnel for forcing air axially therethrough, a pair of parallel and inclined perforated walls extending across the other end of said housing, the perforations in one of said walls being smaller and more closely spaced than those in the other wall, said walls being separated by an open space to permit unrestricted flow of air therebetween, a liquid proportioning device for mixing water and a bubble-forming wetting agent, and conduit means connected to said proportioning device and having a discharge opening in the space between the walls at the tops thereof for injecting the mixture of water and wetting agent directly into the space between the walls at the tops thereof whereby the solution will flow downwardly through the walls.

References Cited in the file of this patent UNITED STATES PATENTS 1,051,661 Anderson Jan. 28, 1913 2,133,499 Dolan Oct. 18, 1938 2,137,905 Church et a1 Nov. 22, 1938 2,225,702 Lyon Dec. 24, 1940 2,322,110 Bock June 15, 1943 2,356,757 Fleisher Aug. 29, 1944 2,535,386 Brookins Dec. 26, 1950 2,599,796 Wicklander June 10, 1952 2,645,292 Williams July 14, 1953 2,776,716 Wicklander Jan. 8, 1957 FOREIGN PATENTS 292,951 Switzerland Aug. 31, 1953 

